Apparatuses, methods and systems for parking brake tensioning fixture

ABSTRACT

The present invention provides a parking brake tensioning apparatus, method, and system. Generally described, the device is for adjusting the tension cable of a parking brake in a vehicle. The device has an inner housing for receiving the handle of the parking brake. Also, the device has a deformable member attached to the housing, and is preloaded with a predetermined load. The device further has a force probe, or rod, having a first end connected to the deformable member and a second end in contact with a component of the vehicle. In addition, the device has a switch for generating a control signal when a predefined force value is applied to the deformable member by adjusting the tension of the tension cable through an adjustment tool. Furthermore, the device has a relay for transmitting the control signal to the adjustment tool once the predefined force value is reached, thus disabling the adjustment tool. Other embodiments are also claimed and described.

RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication Ser. No. 60/603,137, filed on 20 Aug. 2004. U.S. ProvisionalPatent Application Ser. No. 60/603,137 is hereby incorporated byreference herein as if fully set forth below.

TECHNICAL FIELD

The present invention relates generally to parking brakes and moreparticularly, to a device for adjusting the tension cable of a parkingbrake.

BACKGROUND

One of the last operations performed on an automobile before it rollsoff the production line is adjusting the tension of the manual parkingbrake system. Properly adjusting the parking brake system is of greatimportance for several reasons. First is safety. If a parking brakesystem is improperly adjusted, a vehicle operator may have a false senseof security regarding the effectiveness of the park brake system. Forexample, when the employee drives the automobile off the productionline, he or she will typically engage the manual parking brake once theypark the automobile in the storage lot. If the parking brake is set tooloose, the automobile may begin to unintentionally roll from itsstationary position, thereby posing a potential threat to the safety ofthe employee, the condition of the automobile, other automobiles withinthe storage lot, and the production facility. Moreover, this sense ofsecurity will flow to the consumer, who, as a result of an improperlytensioned parking brake system, may be at risk of personal injury, theinjury of others, or the injury of property.

Second, the proper tensioning of the parking brake system creates aperception of quality to the consumer. If the tension of the parkingbrake is set appropriately, the consumer will regard this as anindication of high build quality. If the tension of the parking brake,however, is improperly set, the potential consumer may view this as asign of poor vehicle refinement. This is especially true of highperformance vehicles such as the Mustang, manufactured by the Ford MotorCompany, of Dearborn, Mich.

Unfortunately, the cables of a parking brake system are inherentlydifficult to tension properly, particularly in a production environmentthat is accustomed to using torque specifications for securingfasteners. The typical tools used for adjusting to a given torquespecification include pneumatic wrenches or direct-current (DC)electrical wrenches. These tools have proven to be capable of tighteningto the design specifications of a vehicle. The threaded rod and theadjustment nut seen in many cable tensioning systems, however, do notexperience the typical clamp loads and require very little torque to beadjusted properly.

Current efforts to adjust the tensioning of the parking brake are to usea torque wrench to tighten the adjustment nut attached to the end of thecable. The torque wrench is set with a predefined torque specificationand the adjustment nut is tightened until the desired torque isachieved. This adjustment strategy has several shortcomings fortightening a cable system such as those seen in vehicle parking brakes.First, merely setting the torque on the adjustment nut may result inwide variations cable tension from one automobile to another. Forexample, the parking brake tension of one automobile may have thepredefined torque specification as low as 1.9 Newton-meters (N-m), whichis well below the lower limit for reliable operation of the operation ofconventional pneumatic tools. As a result, the need of a power orelectrical wrench is usually necessary. Another shortcoming is that theprevailing torque on the fastener is highly variable due to themanufacturing tolerances and environmental conditions, which candrastically alter the required torque to properly adjust the parkingbrake. Combined with such a low torque specification, it is nearlyimpossible to set a torque target that matches the desired cabletension.

Problems commonly arise without proper parking brake adjustment.Under-tension is one problem that can result by improperly adjusting aparking brake. If a parking brake system is under-tensioned, the parkingbrake will have free-play. Free-play is where the handle of the parkingbrake can be pulled some distance before any tension is applied to theparking brake cable. This looseness in the system is perceived by thecustomer as an indicator of poor build quality. In extreme cases, thiscan cause an operator of the vehicle to believe the vehicle is properlysecured after applying the parking brake, where the brake is actuallynot yet engaged. Conversely, over-tension is another result of improperparking brake adjustment. In an over-tension system, the parking brakemay be applied when the operator believes the parking brake isdisengaged. The parking brake cable may apply brake pressure at thewheels of the vehicle, while the parking brake is in the rest position.As a result of over-tension, brake drag is created. Brake drag causesquality and safety concerns, since it can cause accelerated brake wear,and also overheating at the vehicle's wheels.

Therefore, an apparatus, method, and system for properly tensioning aparking brake without relying on a torque specification is needed toensure quality production.

SUMMARY

The present invention provides a parking brake tensioning apparatus,method, and system. Generally described, the device is for adjusting thetension cable of a parking brake in a vehicle. The device has an innerhousing for receiving the handle of the parking brake. Also, the devicehas a deformable member attached to the housing, and is preloaded with apredetermined load. The device further has a force probe, or rod, havinga first end connected to the deformable member and a second end incontact with a component of the vehicle. In addition, the device has aswitch for generating a control signal when a predefined force value isapplied to the deformable member by adjusting the tension of the tensioncable through an adjustment tool. Furthermore, the device has a relayfor transmitting the control signal to the adjustment tool once thepredefined force value is reached, thus disabling the adjustment tool.

The inner housing of the device also can have a clamp to engage thehandle of the parking brake and securing it within the inner housing.The clamp may be a self-actuating cam, or a lever-actuating clamp.Further, the device also has a lever attached to the clamp which is usedto disengage the clamp, and thus the handle from the inner housing ofthe device.

The device, furthermore, can have a foot that is attached to the forceprobe, or rod. In this embodiment, the force probe is attached to thedeformable member and the foot. The foot can be attached to the forceprobe by a threaded screw-like method.

The adjustment tool can be a handle-based tool to apply the force to thetension cable. In a particular embodiment, the adjustment tool is adirect current electric wrench that assists with applying tension to thecable.

The deformable member can, for example, be a spring. The spring can beloaded with a predetermined load value to accurately measure the cabletension within the device. The deformable member can be adjusted byinserting or removing shims to adjust the predetermined load. Thepredetermined load is related to the geometry of the device, and thedesired cable tension in the system. In one embodiment, the load can bein the range of approximately 15-20 pounds.

Additionally, the device can have one or more indicators. Theseindicators can provide feedback to a user of the device when apredetermined value has been achieved in the adjustment of the parkingbrake.

The method of adjusting a parking brake is also described. The rod orforce probe is first preloaded with a predetermined load, whichcorresponds to a first position of the handle of the parking brake. Thehandle can then be inserted into a parking brake fixture attached to theprobe. The force probe is then placed on a component of a vehicle, suchas the center console of the vehicle. The adjustment nut is thentightened, deflecting the handle to a second position, which correspondsto a predefined force value. Once the predefined force value is reached,the force being applied to the tension cable is then disabled.

The system of adjusting a parking cable is also described. The systemincludes an adjustment tool connected to a parking brake fixture foradjusting the tension of a parking brake. The parking brake fixture hasan inner housing, a deformable member, a force probe, a switch, and arelay. When the tension in the cable is adjusted, the handle of theparking brake is deflected, which causes the deformable member tocompress to a predefined force value. The downward deflection of thehandle of the parking brake causes the force probe to contact theswitch, which causes a signal to be sent to the adjustment tool todisable the adjustment tool.

The various aspects of the present invention may be more clearlyunderstood and appreciated from a review of the following detaileddescription of the disclosed embodiments and by reference to theappended drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a parking brake tensioning device in accordance with someembodiments of the present invention.

FIG. 2 depicts a cross-sectional view of the parking brake tensioningdevice in accordance with some embodiments of the present invention.

FIG. 3 is a logic flow diagram illustrating a routine for adjusting thetensioning cable of a parking brake in accordance with some embodimentsof the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a parking brake fixture 100 for adjusting the tension ofa parking brake 115 in an automobile. Typically, the parking brakefixture 100 is placed over a parking brake 115. The parking brakefixture 100 contains a rigid outer housing 105, which is typically madefrom a polymer material, such as DERLIN®, which provides a durable andsmooth finish. The rigid outer housing 105 can also be constructed fromother polymer materials, such as polyolefins, such as, but not limitedto ultra-high molecular weight (UHMW) polyethylenes, low, medium, andhigh density polyethylenes, polyurethanes, polyamides, and copolymers,and combinations thereof. In addition, other materials, including metalssuch as aluminum, titanium, and the like, metal alloys, ceramics, andthe like, can be used for the rigid outer housing 105, without departingfrom the scope of the invention.

The parking brake 100 also includes an inner housing 110 that receives ahand operated parking brake 115, which includes a handle 120 and arelease button 125. The parking brake 115 is typically located withinthe center console of a vehicle, between the driver's side and frontpassenger's side seats and may be found in automobiles, such as the 2005Mustang, manufactured by the Ford Motor Company of Dearborn, Mich.

The inner housing 110 can contain a clamp 130 to secure the parkingbrake 115 within the inner housing 110 of the parking brake fixture 100.The clamp 130 is preferably a self-actuating cam that engages theunderside of the handle 120 of the parking brake 115. In operation, thehandle 120 of the parking brake 115 is inserted into the inner housing110 a sufficient distance, such that the back wall of the inner housing110 engages and depresses the release button 125 of the parking brake115. The clamp 130 simultaneously engages the bottom of the handle 120of the parking brake 115 and exerts and upward force on the handle,thereby locking the handle 120 of the parking brake 115 in the innerhousing 110 and prohibiting the parking brake 115 from disengaging fromthe parking brake fixture 100. The self-actuating cam mechanism can bespring loaded to provide a constant upward force on the handle 120 ofthe parking brake 115. Since the pivot location is located at the frontof the clamp 130, the handle 120 of the parking brake 115 slides easilyinto the inner housing 110. Due to the actuation of the cam, however, agreater upward force is applied if the handle 120 is pulled out.Although the clamp 130 is described as a self-actuating cam mechanism,those skilled in the art will appreciate that the clamp 130 may be apush-down clamp mechanism, a lever clamp mechanism, or any otherclamping mechanism that may be used for securing the handle 120 of theparking brake 115 in the inner housing 110, without departing from thescope of the invention. The corners of the inner housing 110 and theclamp 130 can have rounded corners and sharp edges that have beenrounded over to properly secure the handle 120 of the parking brake 115in the inner housing 110 without causing damage to the handle.

The parking brake fixture 100 also can contain a lever 125. The lever125 acts as a release of the self-actuating cam mechanism. When thelever 125 is depressed, the upward force of the cam mechanism isreleased, which allows the handle 120 of the parking brake 115 to beremoved from the inner housing 110.

The parking brake fixture 100 also includes a force probe 150. In oneembodiment, the force probe 150 is a spring deflection mechanism, whichuses mechanical force applied to a deformable member 215, commonly aspring, to measure the amount of downward force. In another embodiment,the force probe 150 may be an electrical force transducer, whoseresistive value changes as a mechanical force is applied to thetransducer. The change in resistive value can then by measured andconverted to a mechanical force. Although only a spring mechanism and aelectrical force transducer have been described as being used for theforce probe 150, those skilled in the art will appreciate that any typeof force probe, such as a hydraulic force probe and the like, can beused without departing from the scope of the invention.

The force probe 150 can also include a foot 155, which can be attachedto the force probe 150 through a threaded fitting. The foot 155 istypically made from a non-abrasive material and is used to protect theautomotive component, such as a center console of a vehicle, on whichthe parking brake fixture 100 is resting. In one embodiment, the foot155 is made of hard rubber. Other materials that are acceptable for thefoot 155 include polyolefins, polyurethanes, polyamides, andcombinations thereof.

The parking brake fixture 100 also includes an electrical connector 140.The electrical connector 140 allows the parking brake fixture 100 to beattached to a direct current (DC) electrical tool, such as a DCelectrical wrench operating at 24 volts (V) (not shown). In oneembodiment, the electrical connector 140 may be a standard circularindustrial connector, which is well known in the art. The circularindustrial connectors are preferred, since they can withstand productionline conditions in manufacturing environments. The connector 140 mayreceive a connection cable 145 to interface the parking brake fixture100 to the DC electrical wrench through a 24 V input/output (I/O)interface.

The parking brake fixture 100 can also include one or more indicators160 and 165 to provide feedback to an operator of either success orfailure of the parking brake adjustment process. The indicators 160 and165 may be either visual indicators, such as light emitting diodes(LED), light bulbs, and the like, or audio indicators, such as audiotones, or a combination of visual and audio indicators. In oneembodiment, the parking brake fixture 100 includes two visualindicators: a green visual indicator 160 and a red visual indicator 165.The green indicator 160 may be green LED operating at 24 V, which isconnected to a tension rod and is activated when a predefined value isapplied to the force probe 150. The red indicator 165 may be a red LED,also operating at 24 V, that is connected to a controller (not shown),which may be illuminated when an over-torque condition of the DCelectrical wrench occurs, indicating a failure of the tensioningprocess.

The indicator 160 or 165 may need a power supply (not shown) to powerthe indicators 160 and 165. A power supply may be included on theparking brake fixture 100. The power supply may be any power sourceknown in the art for use with electronic devices. For example, a batterymay be used. If a battery is selected, it may be replaceable battery, arechargeable battery, a solar powered battery, and the like.

FIG. 2 depicts a cross-sectional view of the parking brake fixture 100.The clamp 130 is also depicted at the bottom of the inner housing 110.When the handle 120 of the parking brake 115 is inserted into the innerhousing 110, the clamp 130 applies an upward force to the handle 120 ofthe parking brake 115, to secure the parking brake 115 with the innerhousing 110. The lever 135 may be pressed downward to release the clamp130, thereby releasing the force applied to the parking brake 115 andallowing the parking brake fixture 100 to be removed from the handle 120of the parking brake 115. As one skill in the art will recognize, thelever 135 can be implemented to be pushed or pulled to release theparking brake 115.

The force probe 150 has two ends. The first end of the force probe 150can be attached to a deformable member 215. The second end of the forceprobe 150 can be attached to the foot 155 by a threaded screw-likemethod.

The parking brake fixture 100 also includes a deformable member 215. Thedeformable member 215, as one skilled in the art would recognize,relates to devices for absorbing kinetic energy. In an embodiment, thedeformable member 215 can be a spring.

The cross-sectional figure also depicts a brace 205. The brace 205assists in holding the mechanism together. The brace 205, further, canreceive at least one screw 210 to aid stability. The brace is connectedand held together by screw 210. The screw 210 connects the outer housing105 to the brace 205 and aid in stability.

A switch 225 is also depicted in the figure. The switch 225 can be atoggle switch, push button switch, snap action switch, and the like. Ina preferred embodiment, the switch 225 is a push button switch. Upondepression of the switch 225, it triggers a relay. The switch 225 isconnected to a relay 230 and at least one indicator 160 or 165, whichcan provide feedback to an operator of either success or failure of theparking brake adjustment process. The indicators 160 and 165 may beeither visual indicators, such as light emitting diodes (LED), lightbulbs, and the like, or audio indicators, such as different audio tones,or a combination of visual and audio tones. In one embodiment, theparking brake fixture 100 includes two visual indicators: a green visualindicator 160 and a red visual indicator 165. The green indicator 160may be green LED operating at 24 V, which is connected to a force probeand is activated when a predefined preload value is obtained. The redindicator 165 may be a red LED also operating at 24 V that is connectedto a controller (not shown), which may be illuminated when anover-torque condition occurs indicating a failure of the tensioningprocess.

The parking brake fixture 100 focuses on using handle efforts toindicate a properly tensioned parking brake system. It subsequentlydisables a connected adjustment tool, connected by connector 140 andconnector cable 145. Handle effort is the amount of force exerted on aparking brake handle 120, which is a direct measurement of a systemtension, rather than an adjustment nut torque specification. This isbecause the handle 120 removes the effect of thread friction variationand measurement error at low torque.

The measurement of handle effort is more convenient than directlymeasuring the tension of the tension cable of the parking brake, sincethe measurement and system adjustment can be done within the vehicle.This is critical operation and adjustment in a production lineenvironment.

In order to measure handle effort, the parking brake fixture 100 isattached to a handle 120 of parking brake 115. The inner housing 110 ofthe parking brake fixture 100 depresses the lever 125 of the handle 120on the parking brake 115, and rests the force probe 150 of the parkingbrake fixture 100 on the console of the vehicle. The clamp 130 such as aself-actuating cam, lever clamp, and the like can be implemented tosecure the parking brake fixture 100 on the handle 120 of the parkingbrake 115.

Several methods of measuring force may be utilized, including electricalforce transducers and deformable members, such as spring deflectionmechanisms. For reliability and simplicity, a spring deflectionmechanism is preferred. The spring deflection mechanism converts a forceat the handle 120 into a deflection of the force probe 150 of theparking brake fixture 100. By setting a predetermined force value on thespring, the force probe 150 can withstand the effort of the handle 120of the parking brake 115 without moving and will start deflecting onlyafter a force that is greater than the predetermined force value hasbeen exceeded. For this solution, the force probe 150 deflects into aswitch 225, which activates shut-off logic of the adjustment tool.

The tool shut-off logic can include a wireless transmitter/receiver, anda tethered, hard-wired connection. Wireless transmission providesgreater freedom of motion for the operator, but the components tend tobe more susceptible to damage from tool abuse. In addition, theproduction line environment, or manufacturing facility, often has highlevels of electromagnetic interference, which can impair operation andrequire additional components. Implementation of a wireless transmissioncan be achieved by 802.11, Infra-Red, Bluetooth, cellular digital packetdata, high speed circuit switched data, packet data cellular, generalpacket radio service, radio communication, and the like, and anycombination thereof. Further, if wireless transmission is implemented,another power supply may be required. In an embodiment, a battery wouldsuffice. A battery would limit costs, add limited weight, and preventexcessive maintenance costs.

A tethered shut-off connection, however, is a preferred embodiment ofthe present invention; it provides a low cost, simple, and durablesolution. In this particular embodiment, a connector 140, attached tothe outer housing 105 of the parking brake fixture 100, is connected tothe adjustment tool by means of a connector cable 145. In thisembodiment, a switch 225 is toggled by the force on the force probe 150at a predetermined force value. As a result, an electrical circuit isclosed between the adjustment tool (not shown) and the parking brakefixture 100, through the connection of the connector 140 and theconnector cable 145. In a preferred setting of an assembly production,the connection can connect through an input/output port of a directcurrent adjustment tool. In an embodiment, the adjustment tool can be anut runner. By implementing remote shut-off logic in the direct currentadjustment tool's controller, the closed circuit can cut power to theadjustment tool. This adjustment results in little danger inover-tensioning the parking brake system, because the adjustment tool isdisabled at the proper handle effort. There is no additional triggerfrom the operator. In fact, results of this embodiment illustrate asignificant improvement over the prior art of adjusting nuts by thetorque control method.

In an embodiment of the present invention, the adjustment tool can be ahandle-based tool. The handle-based tool is a tool capable of beingmanaged by the operator applying tension to the tension cable of thevehicle. Furthermore, this tool can be held with one or two hands of theoperator. The adjustment tool, also, is an instrument that tightens thetension in the cable. In a preferred embodiment, the tool may be a DCelectric wrench.

FIG. 3 depicts a logic flow diagram illustrating a routine 300 foradjusting the tension of a parking brake 115. Routine 300 begins at 305,in which the load setting on the deformable member 215 is preset to apredetermined value. The predetermined value for the load causes thehandle 120 of the parking brake 115 to deflect to an initial position.For instance, in one embodiment, the predetermined value of the load maybe between 15-20 pounds of force and more particularly to about 20-25pounds of force. The preloaded force on the deformable member 215 may beadjusted by adding or removing a number of shims 220. For example, toincrease the preload on the deformable member 215, more shims 220 can beadded, which will cause the deformable member 215 to be compressed,thereby increasing the load on the deformable member 215. Alternatively,to decrease the preload on the deformable member 215, shims 220 may beremoved; as a result, the removal of a shim 220 decreases the tension onthe deformable member 215, and thereby decreases the preload force.

At 310, the handle 120 of the parking brake 115 is placed in the innerhousing 110. The handle 120 is inserted into the inner housing 110 untilthe parking brake release button 125 fully engages the back wall of theinner housing 110. The bottom of the handle 120 simultaneously engages aclamp 130, which is typically a self-actuating cam, located at thebottom of the inner housing 110. The clamp 130 exerts an upward force onthe handle 120 of the parking brake 115, which then locks the handle 120into the inner housing 110.

At 315, the parking brake fixture 100 is lowered until the force probe150 comes in contact with an automotive component, typically the centerconsole of the vehicle. The preloaded force on the deformable member 215maintains the handle 120 of the parking brake 115 at a first positionabove the center console. At 320, the tension on the tension cable isincreased by tightening a torque nut attached to the tension cable.Typically, the torque nut is tightened with a DC electric wrench, whichis attached to the parking brake fixture by a connector cable 145connected to electrical connector 140. The adjustment tool is activated,which causes the torque nut to tighten. As the torque nut is tightened,the tension on the tension cable increases, which causes the handle 120to deflect downward. The deflection of the handle 120 causes the parkingbrake fixture 100 to move downward and increases the pressure ondeformable member 215, thereby causing the force probe 150 to move in anupward direction.

At 325, a determination is made whether the handle 120 of the parkingbrake 115 has deflected to a second position, which corresponds to apredetermined force load. If the handle 120 of the parking brake 115 hasbeen deflected to the second position, then the appropriate amount oftension has been applied to the tension cable. As a result, the routineis over and the “YES” branch is followed to the “END.” The determinationof whether the handle has been deflected to a second position is madewhen the handle 120 of the parking brake 115 is deflected downward to asecond position, then a control signal is generated and an indicator160, if provided, to an operator signaling that the appropriate amountof tension has been applied to the tension cable. The control signal isgenerated by the force probe 150 being deflected upward until itcontacts a switch 225, which activates the control signal. Additionally,the switch 225 activates a relay 230, which generates a relay signal tothe DC electric wrench. The relay signal is received by the 24 voltinput/output interface, which generates a logic signal to deactivate theDC electric wrench. If, however, the handle 120 of the parking brake 115has not been deflected to a second position, then the “NO” branch isfollowed back to 320, where the tension continues to be applied to thetension cable of the parking brake. The process continues until apredetermined force load is applied to the force probe 150.

The various embodiments of the present invention have been describedwith reference to the above discussed embodiments, but the presentinvention should not be construed to cover only these embodiments.Rather, these embodiments are only exemplary embodiments. Variations ofthe above exemplary embodiments may suggest themselves to those skilledin the art or others without departing from the spirit and scope of thepresent invention. The appended claims and their full range ofequivalents should, therefore, only define the full scope of the presentinvention.

1. A device configured to be used with an adjustment tool for adjustinga parking brake of a vehicle, the parking brake comprising a handle anda tension cable and the adjustment tool adjusting the parking brake bytensioning the tension cable, the device comprising: an inner housingconfigured to receive and selectively retain the parking brake handle; aforce probe being configured to move between a first position and asecond position relative to the inner housing; and a deformable memberconfigured to bias the force probe into the first position relative tothe inner housing, the force probe being configured to move from thefirst position to the second position upon application of apredetermined load to the deformable member, the predetermined loadbeing applied to the deformable member when tensioning of the tensioncable by the adjustment tool causes the parking brake handle to apply aload substantially equal to the predetermined load to at least onesurface of the inner housing, the device further comprising: a switchconfigured to generate a control signal when the force probe moves tothe second position; and a relay configured to receive the controlsignal and, in response to the control signal, cause the adjustment toolto discontinue tensioning the tension cable.
 2. The device of claim 1,wherein the inner housing comprises a clamp for selectively retainingthe handle.
 3. The device of claim 2, further comprising a leverattached to the device operable to release the clamp from the parkingbrake.
 4. The device of claim 1, wherein the deformable member comprisesa spring.
 5. The device of claim 1, further comprising at least oneindicator configured to provide feedback when the predetermined load isapplied to the deformable member.
 6. The device of claim 1, furthercomprising at least one shim to adjust the predetermined load.
 7. Thedevice of claim 1, further comprising an electrical connector configuredto allow the adjustment tool to be in contact with the device.
 8. Thedevice of claim 1, wherein the predetermined load is in the range ofapproximately 15-30 pounds of force.
 9. The device of claim 1, whereinthe predetermined load is in the range of approximately 20-25 pounds offorce.